This invention relates to a fuel injection system for an internal combustion engine for supplying fuel to an intake system thereof, and more particularly to an electronically-controlled fuel injection system of this kind which is adapted for use in small-sized engines equipped with no battery.
An electronically-controlled fuel injection system for an internal combustion engine is conventionally known, which comprises fuel injection valves arranged in an intake system, and control means for controlling a time period over which the fuel injection valves are opened in accordance with operating conditions of the engine.
Such a conventional electronically-controlled fuel injection system requires the use of a battery for supplying electric power thereto for driving, fuel injection valves, a control circuit for controlling the valves, and a fuel pump. Therefore, the conventional electronically-controlled fuel injection system cannot be used in small-sized engines which are equipped with no battery (hereinafter referred to as "batteryless engines" unless otherwise specified).
Under the circumstances, it has been proposed e.g. by Japanese Provisional Patent Publication (Kokai) No. 63-93440, to utilize output power from a generator driven by an engine for electronically controlling fuel supply to the engine, during operation thereof. However, insofar as the problems of fuel supply and power supply at the start of the engine are concerned, there no disclosure except that the engine is equipped with a small battery which consumers only a small amount of electric power and can be charged by the use of part of electric power generated by a flywheel magneto.
Further, concerning the above problems, Japanese Provisional Patent Publication (Kokai) No. 63-170541 discloses the use of a battery having a small capacity, such as a dry cell, for starting a batteryless engine.
Also, Japanese Provisional Patent Publication (Kokai) No. 63-259127 discloses the technique of metering fuel by a device operated by intake vacuum.
Thus, the above prior art publications concerning the electronically-controlled fuel injection system having no conventionally-used battery merely disclose respective techniques which are not related to each other, and no disclosure has been made as to how to combine these separately-proposed individual techniques. More specifically, no disclosure has been made as to relationships between the starting operation of the engine, and fuel supply operation and timing therefor, or relationships between ignition, operation of fuel injection valves, and power supply, etc.